Assigjstob to the been



(Nn-Model.)

A. BERNSTEIN.

AUTOMATIC CCT-CUT FOR ELECTRIC LIGHTS.

Patented Aug. 28, 1883 .y

N. PETERS Pnuxwmhngnrnr. wnmngu.

Niri-n STATES PATENT irrrci.,

ALEX BEENSTEIN, OF BOSTON, MASSACHUSETTS, ASSIGNOR TO THE BERN- STEIN ELECTRIC LIGHT MANUFACTURING COMPANY, OF SAME PLACE.

AUTOMATIC CUT-OUT FOR ELECTRIC LIGHTS.

SPECIFICATION forming part of Letters Patent No. 283,748, dated August 28, 1883.

Application filed February 26,1883. (No model.)

To all who/u, it may concern: Be it known that I, ALEX 'BERNsTEIN, of Boston, in the county of Suffolk and State of Massachusetts, have invented certain Improvements in Automatic Cut- Outs for Electric Lights, of which the following is a specification. f

My invention relates to the application of electricity to the purposes of furnishing illumination or power, or to the employment of the same force in any other art in which the useful effect is obtained through the instrumentalities of some device acted upon by electricity developed at a comparatively distant point and supplied to the said translating` device or instrument by means of suitable conducting-wires. The instrument or device to be actuated may be an electric lamp, an electromotor, a signaling-instrument, or any other instrument adapted to be operated in such a system; but to avoid proliXity I shall herein refer more particularly to electric lamps, especially as my invention is peculiarly an essential feature in systems of electrical illumination. In those systems in which a number of lamps or other centers of electrical work are employed in series it .is obvious that an automatically-operating cut-out or short-circuiting device attached to each of the lamps is absolutely essential in order to prevent the circuit from being broken and the consequent failure, extinguishment, or cessation of operation of all the lamps included therein in case any one of the lamps should become defective or failto conduct the current. Moreover, it is most desirable that the cut-out should be brought into operation before the passage of 'the current is entirely interrupted. In case lamps ofthe type invented by me and described in Letters Patent granted to me therefor January 30, 1883, No. 271,302, are used, it is possible 4that disintegration of the carbon and arcking resulting therefrom may occur by reason of some defect in the carbon or` in the glass bulb inclosing the same, and consequent leakage. In such a contingency the lamp presents an abnormally high resistance to the passage of the current, the current is proportionally diminished in strength, and the other lamps in the same series commence to give less light. This result takes place before the faulty lamp becomes actually disabled, and

I same immediately.

This has heretofore been accomplished by arranging parallel to the lamp-circuit a normally-closed shunt-circuit, through which a portion of the current continually passes, and within which is included a lshort-circuiting device, adapted to become operative when an increased proportion .of the 6o electric current is diverted through the shuntcircuit in consequence of an increased electrical resistance offered by the lamp. To obtain the desired end I make use of an arrangement generally known as the Vheatstone bridge or balance.7 This arrangement is in general use in .connection with a galvanometer as a means of obtaining correct electrical measurenichts, and has also been extensively used in duplex telegraphy. That its adaptation to my 7o purpose may be fully understood, I will briefly recapitulate the principles of operation, and inasmuch as in such recapitulation it will be Vconvenient to refer to the drawings which accompany and illustrate this specication, I

will first mention the characteristic features of the different figures in the said drawings.

Figure 1 is a diagram of the ordinary theoretical arrangement of the IVheatstone bridge, showing its combination with a'v cut-out de- 8o vice for the purpose which I have hereinbefore indicated. Fig. 2 is asimilar diagram, showing a modication of the connections of the short-circuiting device. Fig. 3 shows one of the many practical forms of embodying in 8 5 a compact form the required arrangement of circuits, resistances, and electro-magnetic appliances; and Fig. 4L is a detail thereof, showing a mechanical device whereby the cut-out, after being once brought into operation, is re- 9o tained in an effective position.

It is of course not necessary in a Vheatstone bridge that the wires should be arranged in the parallelogrammatic form shown, nor in fact is it often done; but as the principle is more easily referred to and understood when thus arranged, it is usual to adopt that form. When the four wires composing the parallelogram 2, G, 4, and 10 are of eX- actly equal resistance, and by means of main roo conductors 1 and 8, attached to the points a and g, a current of electricity is passed through the system from a to g, the said current will divide at a, half of it going through 2 and G and the other half through 4 and I0 to point 105 it is of course desirable to short-circuit the l g, and thence out by the main wire 8 5 but any electro-magnetic instrument placed in circuit on a wire connected across from j to Z) will not be affected at. all, and no current will pass along the cross-wire as long as 2, (i, 4t, and l() are of equal resistance. Again, when 2bears the same proportion to 6 that 4 does to 10, no current will pass from f to Z) through the cleotro-magnet M, but if that proportion is destroyed a current at once flows through the cross-wire, and any instrument included in circuit therewith is brought into action.

I arrange the lamp in circuit in one ol' the arms of the system and an electro-magnetic apparatus in the cross-wire or bridge, the latter being electrically disposed in accordance with the principles hereinbefore enunciated, so that no current -llows through the coils or' the cut-out actuating device so long as thelamp oi'li'ers its proper and normal resistance.

Il', however, from any cause, as explained above, the resistance ofthe lamp becomes abnormal and the lamp is in danger of being tinguished, the equilibrium ofthe bridge system will be disturbed and the cut-out becomes operative. In Fig. 1 the arrangement is shown theoretically. Theincoming maincircuit wire is shown at 1, and, reaching the point a., divides itself into two branches, one leading from the point c by wire 2, resistance R, point j", resistance It', and wire 6 to the point g, the other leading from point u. by wire 4t, lamp Z, point I), wire l0, and rcsistan'ee R2 to the point g. At this point g the branch circuits reunite and pass out by the wire S. From the point f, at the junction of the branches 2 and 6, to the opposite point, b, at the `junction of the branches 4L and l0, extends a cross-circuit or bridge, composed or' the wires 5 and 9 and the electro-magnet H, through the coils of which the said cross-circuit passes. From the point c a wire, 3, leads to iixed contact c, and from the point g another wire, 7, leads to the armature-lever rl of the bridge-wire electro-magnet M, this lever beingsuitably pivoted and normally retracted from the electro-magnet coref, owing to the non-magnetic condition of the core and to the retractile power of the spiral spring c. A limit-screw, 7L, prevents the lever from being retracted too far. As sh'own in the figure, the armature-lever d is at its free end adapted to make contact with the iixed contact-point c, but normally does not make such contact, owing to the hereinbefore described rctractilc devices. Ii' from any cause the core j ot' the bridge-magnet M should become energized, it is evident that the lever d would bc thereto attracted, and that its free end would make contact with the point c, thus establishing a short circuit -between the points c and g. In the figure the current is represented as proceeding in the direction of the arrows. lntering the system at a, and going out at g between those points, the current necessarily divides itself at the former point and traverses both circuits, the amount of current passing through eacl being inversely proportional to their respective resistances. The lamp Z, which we will suppose to have a resistance of four ohms, is included in the branch -lbetween a. and b. The branch l() includes, between and g, a resistance ol' one twenty-lilith (13) of an ohm; branch 2, between c and j', contains a resistance ol' four hundred ohms, and branch G, between j and y, a resistance oi' i'our ohms. In this case, and as long as the lamp is in good order, no current will `tlow in the bridge-wire, and the electro-magnet contained therein remains inert, and the cut-ont circuit conscquently remains open, because the proper proportion between the branches being maintained the system is in equilibrium; but as soon as any defect' occurs in the lamps, by which its resistance is .increased or its integrity impaired, a current will commence to iiow in the bridge-wire 5 between f and b, producing a magnetic effect in the eorej or' the electro-magnet` M, which then actuates the eut out by attracting the armature -levelz NVhen the contact at c is thus made, a line ol' very low resistance is established between n. and g, and the greater portion ot' the current traverses the same. This device therefore prevents the integrity of the circuit from being depcndeiit upon the individual perfection of each and every lamp in the series, as it would otherwise be.

There are many ways in which the principles underlying my invention may be embodied in a practical form. One ol" these is shown in Fig. 3, wherein the principal features of the cut-out apparatus are put together in a compact and condensed form.

A represents in section a case or box in which the working parts are inclosed. In the center thereot` I place the electro-magnet M oi' the bridge-wire, whichis provided with a soltiron core, j, this being capable of :uljustment7 if necessary, by means ofthe screw o and locknut (l at the rear.l A spring-lever, (l, is l'astcned to a screw, s, and is provi ded with an armature, t, by which it is drawn forward when the core 7' is magnetized. At other timesitis retracted either by its own resiliency or by a suitable retraetile, which is not shown. In the present ease the inherent resiliency ofthe form of lever shown issutlieient. The i'ree end of this lever has a contact-piece, fr, which, when the armature. is attracted, is brought against the fixed contact-point c, closing the short circuit. This lixed contactis supported by a metal bracket, 7, which depends :from and is in electrical connection with the screw-post y'. The screw-posts (rand f/ are terminals ot' the system.

Surrounding the electro-magnet M, and separated therefrom by an air-space, is a resistance-coil; It, and on the end ot' this coil is another and smaller coil, It. The only objects ot' arranging the resistance-coils in this i'orm are the convenience and compactness so obtained, no special electrical ei'lect being either intended or desired. A sliding spindle, p, slides through a small hole in one corner o1' ICO IIO

IIS

esame A 3 the apparatus, and at its lower extremity is shouldered. rIhis spindle is guided and kept in place by passing through the bracket-block v7 to terminal g.

o. The shouldered portion m of the spindle end rests on the free end of the armature-lever, and the lower part, h, serves as a back limit for the armature-lever d. This portion of the apparatus is more clearly shown in Fig. et, in which the external case, A, and the devices attached thereto are in section. The resistance-coils and electro-magnet are both inclosed in a surrounding case, B, from which the core j projects. As shown, the armaturelever is inert, and rests on its back limit, the spindle end m being elevated and supported upon the extreme .end of the same lever.

In Fig. 3 the lever is in its forward position, the points w and c being in contact, while the spindle end m, :no longer supported by the end of the lever, has fallen into the space between the back ofthe lever d and the flat surface of the bracket-block 0,"thus serving as a wedge, whereby the Acontacts are firmly maintained, although the actuating-magnet M may be demagnetizedas soon as the short circuit through the contacts is completed.

I will now trace the circuitsthrough the apparatus shown in Fig. 3, and it will be seen that they correspond with the theoretical arrangement in Fig. 1. The line-circuit, coming in, is united to the terminal a. From there it divides, as indicated above, the line representing the lupper circuit in the diagram passing by wire 2 to the large resistance-coil It, thence to the point f and smaller resistance, R,which is divided from the larger by the non-conducting vpartition z',- leaving It by the wire 6, it passes then to the terminal g and out by wire 8. The wire representing the branches 4' and 10 in the diagram may be traced as follows: from the terminal a, by wire et to the lamp Z, thence to the point b, and by wire l0, through the small resistance R2, to the terminal f/ and out to wire 8.

The cross-wire or bridge cir-cuit may be traced from the point f to the electro-magnet M, then by wire9 to the opposite point, b. The short-circuit or cut-out wire is led from screwpost a by wire 3 to screw s, thencethrough the armature-lever d and contacts c andx and arm In practice all the wires would be placed inside the case, but I have shown them separate for greater clearness.

Instead of adopting the mechanical retaining device shown in Fig. 4, I may allow the armature k, when attracted, to come into absolute Contact with the core j, where, after the cessation of the cross-wire current, it may be held by residual magnetism.

The short-circuiting device may be so arranged as to cut out the whole of the bridge system and connect the points a and g direct, as hereinbefore described, and shown in Figs. l and 3, or it may be arranged to cut out only a portion of the arrangement, as shown in Fig. 2, where the resistance R onlyv can be shortcircuited. It is sometimes very advantageous to adopt this method, and in that case the reresistance of four ohms `betweenl f and g is left in the circuit, instead of the resistance of the lamp. ever, necessary to construct the said resistance' in such a way as to be capable of conveying strong currents of electricity without detriment to the wire. Moreover, when this method is employed I am enabled to dispense w-ith retaining devices whereby the contacts of the short-circuit or cut-out wire are kept together, inasmuch as the current, after passing through the said cut-out wire and arriving at the point f, will there divide between the resistance R( and the cross-wire A large proportion of the current will take the latter route, passing through the wire 5 and t-he actuating-magnet M to point I), and thence by wire 10, resistance R2, to g and out. It is therefore clear that the electro-magnet will in this case retain its attractiveA power, and will not allow the armature-lever to fall back. No mechanical retainer thereforelis necessary. rIhe specific resistances which I have named are ofcourse not essential, but merely illustrative.

Any resistance will answer, so long as the proper proportions are preserved, and those in the branches 2, 6, and 10 are dependent on that of the lamp.

I claim- I. In a system of electrical illumination wherein the lamps are arranged in series, the combination, at each light center, of a main or supply circuit, a Wheatstone bridge, an electric lamp in one ofthe arms ofthe bridge, resistances bearing a definite ratio to the said lamp and to one another in the other arms of the bridge, whereby equilibrium may normally be maintained in the cross-wire, an electromagnet in the cross-wire thereof, and a normally-open or incomplete short-circuiting or cut-out wire extending between the terminals of the bridge, controlled by the armature of said electro-magnet and adapted to be closed by the same when the electro-magnet becomes energized, substantially as described.

. 2. rIhe VVheatstone bridge or balance at each lighting center, in combination with an electric lamp in one of the branches thereof, a shortcircuiting apparatus, and an electro-magnetic actuating device therefor, substantially as described.

3. A cut out apparatus for an electric lamp, consisting of a Vheatstone bridge or balance having the lamp included in one of its branches and resistances bearing a definite ratio to the said lamp and to one another in the other-branches, whereby equilibrium may normally be maintained in the cross-wire, a normally-open short-circuit wire extending between the terminals of the bridge and adapted, when closed, to cut out all of the bridge resistances, and an actuating electro-magnet in the cross-wire of the bridge, adapted by the attraction of its armature to close the normally-open short circuit and cut out the resistances, vas described.

Vhen this is done, it becomes, howy IOO 4. The combination, in an electric lighting apparatus, of an electric lamp placed in a branch of a lVheatstone bridge, a short-circuiter therefor, an actuating electro-magnet in the cross-wire of the bridge, adapted to become operative when the equilibrium of the bridge is disturbed by reason of the lamp becoming defective or offering an abnormal resistance, and thereupon to close the short eircuit, and a retaining device whereby the short circuit, when once made, is maintained, substantially as described.

5. An electric-light short-circuiting apparatus, consisting of the following instrumentalities: an electric lamp in one or' the branches of a Vheatstone bridge, resistances bearing a denite ratio to the said lamp and to one another in the other branches of the bridge for the purpose of normally maintaining equilibrium in the cross-wire, an electro-magnet in the cross-wire, adapted upon any change in the resistance of the several branches of the bridge to become operative, anda short-circuiting line extending from the entering terminal ol" the bridge to one of the crosswire junctions, adapted to be brought into action bythe electro-magnet and to shunt the lamp and the greatest branch resistance, but to leave the cross-wire and electro-magnet in a branch circuit, whereby a portion of the current is diverted continuously through the said electromagnet after the establishment of the short circuit, thus retaining the said short circuit closed after itis once established, substantially as described. t

(i. In an electric lighting system, the combination of an electric lamp andan automatic short-cireuiting device therefor, the said lamp being connected in one ot' the arms of a Vheatstone bridge, which has an electro-magnet ineluded in its cross-wire, and which, when the lamp is in its normal condition, is in equilibrium, and the said short-circuiting device being adapted to be actuated by the cross-wire electro-magnet and to short-circuit the lamp when the equilibrium of the bridge is disturbed by reason of any change in the electrical resistance of the lamp.

7. The combination, with an electric lighting circuit and a lamp at any station thereof, of a Vheatstone bridge having the lamp in one of its branches and resistances in its other branches, one of the said resistances bearing a definite ratio to the lamp and the others a like ratio to one another, an electro-magnet in the cross wire ot' the bridge, normally inoperative but adapted to become operative on any change in the resistance of the lamp, and a normallyopen short circuit connected with one ol' the terminals of the bridge and with one of the cross-wire junctions, and actuated by the said eleetro-n1agnet when the equilibrium of the bridge is disturbed to shunt the lamp and a portion onlypf ther other resistances, substantially as dseribed.

S. A translating device and a resistance bearing a definite proportion thereto in eircuit between two main-line terminals, in combination with a constantly-closed parallel circuit, which includes two other resistances, one of which bears the same ratio to the translating device that the other bears to the ixed rc sistance in the circuit with the said translating device, the said parallel circuit being connected at its ends with the main-line tern'xinals ofthe lamp-circuit, a cross-wire, comprising an electro-magnetic helix, united to both wires and extending from a point in one of the circuits to a point proportionatel)T corresponding in electrical resistance thereto in the other, and a normally-open short circuit of very low resistance extending also between the main-line terminals and adapted to be closed or made continuous by the euergization ot' the cross wire magnet upon any change in any ot' the four resistances, substantially as set forth.

9. The combination, substaiitially as hereinbefore described, of a main electric lighting circuit, a series of electric lamps disposed scrially in the said circuit, and an automatic cut-out for each lamp, consisting of an electromagnet placed in the cross-wire o't'a Vheatstone bridge which includes the lamp in one of its branches and resistances bearing adelinite ratio to the said lamp and to one another in its other branches, whereby equilibrium may normally be maintained in the cross-wire, the said el ectro-niagnet being adapted to remain inert so long as the resistance ot' the lamp remains normal, but to become operative when the equilibrium of the bridge is disturbed by any change in the resistance of the lamp, and a norniallyopen short circuit round the lamp, and also round the other ln'idge-rcsistailees, adapted to be actuated by the electro-magnet in the cross-wire when the said magnet becomes operative, whereby the .lamp yand the other resistances may be sl1o1.t-cii.cuitcd, lor the purposes speciiied.

10. rlhe combination, with an electric lamp, of the electro-niagnet M, the high resistance l?, and the resistance It', bearing a definite ratio thereto, surrounding the clectro-magnet, the armature-lever d, and bracket 7, forming part of a normally-open short circuit, and the sliding spindle p, the said electro-magnet being normally neutral, but adapted to become e11- ergizcd and to bring its armature into contact with the bracket 7, when the lamp shall otter an almormally-high resistance to the passage ol' the current, and the said sliding spindle being constructed and adapted to i'all between the armature-lever and the back limit thereofl on the advance of the former, whereby the said. armature-lever, after being once drawn 1'or ward, is retained in contact with the bracket, substantially as and for the purposes described.

In testimony whereof` I have signed my name to this specification, in the presence o1 two subscribing witnesses, this 21st day oli' llebruary, 1883.

lVitnesses: ALEX BERNSTEIX.

J. H. Grrnnvnn, D. E. RICHARDS.

IIO 

